The intensity of magnetisation $I$ is plotted against the magnetising field $H$ for different substances. The curves $A$ and $B$ shown in the adjoining figure are associated with

The coercivity of a magnet is $5 \times 10^3 \text{ A/m}$. The amount of current required to be passed in a solenoid of length $30 \text{ cm}$ and the number of turns $150$,so that the magnet gets demagnetized when placed inside the solenoid is ............. $A$.

If the given figure shows the relation between magnetic field ($B$ - along $y$-axis) and magnetic intensity ($H$ - along $x$-axis) of a ferromagnetic material,then the point that represents the coercivity of the material is

$A$ metal rod is subjected to cycles of magnetisation at the rate of $42 \ Hz$. The density of the metal is $6 \times 10^3 \ kg \ m^{-3}$ and its specific heat capacity is $0.1 \times 10^3 \ cal \ kg^{-1} \ ^{\circ}C^{-1}$. If the area of its $B-H$ loop corresponds to an energy density of $10^{-2} \ J \ m^{-3}$,then the rise in its temperature in one minute is: (in $^{\circ} C$)

If the $B-H$ curves of two samples of $P$ and $Q$ of iron are as shown below,then which one of the following statements is $CORRECT$?

The energy dissipated per unit volume per cycle in the hysteresis of an iron sample of mass $10 \, kg$ is $200 \, J \, m^{-3} \, cycle^{-1}$. The density of iron is $7500 \, kg \, m^{-3}$. The loss of energy per hour at $50 \, cycle \, s^{-1}$ is: (in $J$)